Hotspot Mitigating With Obliquely Finned Microchannel Heat Sink—An Experimental Study

Abstract

Sectional oblique fins are employed, in contrast to continuous fins, in order to modulate the flow in a microchannel heat sink. The breakage of continuous fin into oblique sections leads to reinitialization of boundary layers and generation of secondary flows that significantly enhance the cooling performance of the heat sink. In addition, an oblique finned microchannel heat sink has the flexibility to tailor local heat transfer performance by varying its oblique fin pitch. Clusters of oblique fins at higher density can be created in order to promote a greater degree of boundary layer redevelopment and secondary flow generation to provide more effective cooling at the high heat-flux region. Thus, the variation of oblique fin pitch can be exploited for hotspot mitigation. Experimental studies of a silicon chip with two hotspot scenarios show that the temperature hike and the temperature difference for the enhanced microchannel heat sink with variable pitch are reduced by as much as 17.1°C and 15.4°C, respectively. As a result, temperature distribution across the silicon chip is more uniform. In addition, the associated pressure drop penalty is much smaller than the achieved heat transfer enhancement, rendering it as an effective hotspot mitigating strategy for the single-phase microchannel heat sink.Index Terms-Enhanced microchannel, hotspot cooling, oblique fins, variable pitch.

Investigation of fluid flow and heat transfer in wavy micro-channels with alternating secondary branches

“…This amounted to a thinner thermal boundary layer and also a steeper velocity gradient closer to the surfaces of heat transfer. That together with the improved extent of span-wise mixing translated to better heat transfer performance which outweighed the miniscule pressure drop penalty incurred [23][24][25].…”

Energy efficient hotspot-targeted embedded liquid cooling of electronics

“…However, these approaches are limited by low device efficiencies, low heat flux pumping capacities and contact parasitic resistance for the former [24] and relatively low heat fluxes for the later [25]. Attempts using single phase liquid cooling have also been reported with varying degree of success [26][27][28]. Additionally, conventional backside attached MMC heat sinks are thermally joined to the chip through a thermal interface material (TIM) which, combined with the thickness of substrate and heat sink base, results in heat spreading and high thermal resistance.…”

Liquid cooling of non-uniform heat flux of a chip circuit by subchannels

“…The effect of using oblique fins was investigated numerically by Lee [19] and experimentally by Lee [20]. Their analyses confirmed that the use of oblique fins led to a decrease in both the chip temperature and temperature difference above the chip surface.…”

“…Their analyses confirmed that the use of oblique fins led to a decrease in both the chip temperature and temperature difference above the chip surface. In addition, varying the fin density according to the heat dissipated at the hotspot improved temperature uniformity [20], but led to an increased pressure drop.…”